I'm a non-native speaker and confused by the pronunciation of "er" in American English,especially the "er"s preceded by "t","l","d",such as "dollar""reporter""matter".Could you tell me in detail how to pronounce them correctly ,like how to move the tongue,etc.
Thank you so much!

yeah,i listen to them like a million times,but i still cant figure out how the native pronounce them,there's still differences between my pronunciation and the natives when i try to mimic the pronunciation.Thus,could any native speaker just clue me in?
Thank you!